12 April 2011

KIDNEY STONES IN ADULTS

Introduction to the Urinary Tract

The urinary tract, or system, consists of the kidneys, ureters, bladder, and urethra. The kidneys are two bean-shaped organs located below the ribs toward the middle of the back. The kidneys remove extra water and wastes from the blood, converting it to urine. They also keep a stable balance of salts and other substances in the blood. The kidneys produce hormones that help build strong bones and help form red blood cells. Narrow tubes called ureters carry urine from the kidneys to the bladder, an oval-shaped chamber in the lower abdomen. Like a balloon, the bladder's elastic walls stretch and expand to store urine. They flatten together when urine is emptied through the urethra to outside the body.

What is a kidney stone?A kidney stone is a hard mass developed from crystals that separate from the urine and build up on the inner surfaces of the kidney. Normally, urine contains chemicals that prevent or inhibit the crystals from forming. These inhibitors do not seem to work for everyone, however, so some people form stones. If the crystals remain tiny enough, they will travel through the urinary tract and pass out of the body in the urine without being noticed.Who gets Kidney Stones?
Stones occur more frequently in men. The prevalence of kidney stones rises dramatically as men enter their 40s and continues to rise into their 70s. For women, the prevalence of kidney stones peaks in their 50s

What Causes Kidney Stones? Kidney stones are hardened crystal clumps that can develop in the urinary system. They usually form because there is a breakdown in the balance of liquids and dissolved solids in the urine. The kidneys must keep the right amount of water in the body while they remove materials that the body cannot use. If this balance is disturbed, the urine can become overloaded with substances (usually small crystals) that won't dissolve in water. Crystals begin to stick together and slowly add layer upon layer to form a stone. A kidney stone may grow for months or even years before it causes a problem.

What are the symptoms?Kidney stones often do not cause any symptoms. Usually, the first symptom of a kidney stone is extreme pain, which occurs when a stone acutely blocks the flow of urine. The pain often begins suddenly when a stone moves in the urinary tract, causing irritation or blockage. Typically, a person feels a sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen. Sometimes nausea and vomiting occur. Later, pain may spread to the groin.

If the stone is too large to pass easily, pain continues as the muscles in the wall of the tiny ureter try to squeeze the stone along into the bladder. As a stone grows or moves, blood may appear in the urine. As the stone moves down the ureter closer to the bladder, you may feel the need to urinate more often or feel a burning sensation during urination.
If fever and chills accompany any of these symptoms, an infection may be present. In this case, you should contact a doctor immediately.

How are Kidney Stones diagnosed?Sometimes "silent" stones-those that do not cause symptoms-are found on x rays taken during a general health exam. If they are small, these stones would likely pass out of the body unnoticed.
More often, kidney stones are found on an x ray or sonogram taken on someone who complains of blood in the urine or sudden pain. These diagnostic images give the doctor valuable information about the stone's size and location. Blood and urine tests help detect any abnormal substance that might promote stone formation.
The doctor may decide to scan the urinary system using a special test called a CT (computed tomography) scan or an IVP (intravenous pyelogram). The results of all these tests help determine the proper treatment.

How are Kidney Stones treated?Fortunately, surgery is not usually necessary. Most kidney stones can pass through the urinary system with plenty of water (2 to 3 quarts a day) to help move the stone along. Often, you can stay home during this process, drinking fluids and taking pain medication as needed. The doctor usually asks you to save the passed stone(s) for testing. (You can catch it in a cup or tea strainer used only for this purpose.)

The First Step: PreventionIf you've had more than one kidney stone, you are likely to form another; so prevention is very important. To prevent stones from forming, your doctor must determine their cause. He or she will order laboratory tests, including urine and blood tests. Your doctor will also ask about your medical history, occupation, and eating habits. If a stone has been removed, or if you've passed a stone and saved it, the laboratory should analyze it because its composition helps in planning treatment.

Lifestyle ChangesA simple and most important lifestyle change to prevent stones is to drink more liquids-water is best. If you tend to form stones, you should try to drink enough liquids throughout the day to produce at least 2 quarts of urine in every 24-hour period.

Medical TherapyThe doctor may prescribe certain medications to prevent calcium and uric acid stones. These drugs control the amount of acid or alkali in the urine, key factors in crystal formation

Surgical TreatmentSurgery should be reserved as an option for cases where other approaches have failed. Surgery may be needed to remove a kidney stone if it

- does not pass after a reasonable period of time and causes constant pain
- is too large to pass on its own or is caught in a difficult place
- blocks the flow of urine
- causes ongoing urinary tract infection
- damages kidney tissue or causes constant bleeding
- has grown larger (as seen on followup x ray studies).

Extracorporeal Shockwave Lithotripsy

Extracorporeal shockwave lithotripsy (ESWL) is the most frequently used procedure for the treatment of kidney stones. In ESWL, shock waves that are created outside the body travel through the skin and body tissues until they hit the denser stones. The stones break down into sand-like particles and are easily passed through the urinary tract in the urine.
Extracorporeal shockwave lithotripsy There are several types of ESWL devices. In one device, the patient reclines in a water bath while the shock waves are transmitted. Other devices have a soft cushion on which the patient lies. Most devices use either x rays or ultrasound to help the surgeon pinpoint the stone during treatment. For most types of ESWL procedures, anesthesia is needed.
In most cases, ESWL may be done on an outpatient basis. Recovery time is short, and most people can resume normal activities in a few days. Complications may occur with ESWL. Most patients have blood in their urine for a few days after treatment. Bruising and minor discomfort in the back or abdomen from the shock waves are also common. To reduce the risk of complications, doctors usually tell patients to avoid taking aspirin and other drugs that affect blood clotting for several weeks before treatment.

Another complication may occur if the shattered stone particles cause discomfort as they pass through the urinary tract. In some cases, the doctor will insert a small tube called a stent through the bladder into the ureter to help the fragments pass. Sometimes the stone is not completely shattered with one treatment, and additional treatments may be needed. ESWL is not ideal for very large stones.